The first emergency call came into the sheriff's department at about 4:17 p.m., Solano County Sheriff Brad DeWall said.

Chris Gerz was working outside when he heard the commotion and looked up into the sky.

"I heard a crack in the sky and a pop. I thought it collided with somebody. But there was nothing else, nobody else in the air," Gerz said. "But, once that happened, it was a free fall."

The plane landed beside Gerz's family ranch.

Witnesses said the small experimental plane spiraled downward, like a corkscrew before crashing into the ground. It also appeared a wing separated from the aircraft.

"A friend of mine who also saw it said his wing came off and it went straight down," said Gerz.

The plane's right wing landed in the center divide of interstate 505. Fortunately, the plane didn't hit any drivers.

"The aircraft landed 30 feet on the east of the northbound 505," said Chris Parker with Solano County CHP. "At the time it came down, nobody was in danger."

Friends have identified the pilot as Jeff Sharman of Vacaville.According to theSolano Pilots website, friends saidSharman was referred to as the "Gnome," the one people went to when it came to figuring out how to fix something on a plane.

According to the CHP, Sharman was flying from Yolo Airport and headed back to the Nut Tree Airport in Vacaville when he crashed.

Friends said Sharmon was doing what he loved when he died--flying.

The FAA and National Transportation Safety Boardare investigating the cause of the crash.